Intercommunicating telephone.



H. G. THOMSON.

INTERGOMMUNIGATING TELEPHONE.

APPLICATION FILED MAR. 30, 1907.

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UNITED STATES PATENT OFFICE.

HENRY c. THOMSON, or BOSTON,' MASSACHUSETTS, ASSIGNOR TO ELECTRIC GOODS MANUFACTURING ooMPANY, OF BoSToN,MASsAcnUSETTs, A CORPORATION OF MAINE.

INTERcoM UNIcArINe TELE1 HoNE.

Specification of Letters Patent. Application filed. March 30,1907. Serial No; 365,490.

Patented Feb. 2, 1909.

simple, efficient and inexpensive form of switch mechanism which may be readily mounted in the casing and which will be positive in actionand not order. V

To this end the invention consists in the features and combinations of parts as hereinafter described and more particularly pointed out in the claims. 1 j I The various featuresiof the invention will be readily understood from the following detailed description of the mechanism shown in the accompanying drawings which embodies these features in the formsin which I prefer to employ them. i

In these drawings-Figure 1 is an elevation of the switch mechanism showing the same mounted within'a telephone box or casing. Fig. 2 is a side elevation of the mechanism. Fig. 3 is a vertical sectional view through one row of push buttons or plungers. Fig. 4 is an end View looking upward in Fig. 2, the front of the telephone boxbeing shown in section; and Figs. 5 and 6 are views similar to Fig. 1 showing the parts in different posltions.

As shown in the drawings the switch mechanism is mounted within a telephone box 1 and is provided with a series of push buttons or plungers 2 which project through the front 8 of the; telephone box. v The plungers 2 are held normally in projected position by s rings 4 which are interposed between the eads of the plungers and a metal plate 5. The plungers project through the plate 5 with which theyhave a sliding contact and are provided with enlarged portions or collars 6, the rear faces of which are held normally against the plate 5 by the springs 4. The front faces of the collars 6 are conical for a purpose to be described.

liable to get out of In front of the collars 6 the plungers are provided with a conical head 7 'Wll10l1 is somewhat smaller in diameter than the collars 6.

The metallic plate 5 is in circuit with the telephone instruments mounted upon the box 1 through a Wire 8 which is connected with the plate by means of a clip 9 and binding screw 10. The plate 5 thus forms a contact plate with which each of the plungers 2 is in constant engagement; The contact plate 5 is mounted upon two blocks 11 of insulating material which project beyond the outer edges of the plate and form insulating su ports for a series of contact springs .12. l ere is a contact spring 12 corresponding. to each of the plungers 2 and these springs extend inward in front of the plate 5 and are provided with contact portions 13 lying in t e path of the conical heads 7 of the plungers. These contact springs are provided at their rear ends with outwardly extending slotted ears 14 to which the wires 15 are connected. These wires lead from the respective contact springs to the main line wires for the difierent stations of the system. When any one of the plungers 2 is forced inward the head7 engages the corresponding contact spring 12 and thus connects the corresponding station with the home station. When the plunger 2 is advanced itis retained in position with the head 7 in engagement with the corresponding contact spring b means of a locking plate 16 which is arranged between the two series of plungers and is provided with shoulders 17 adapted to pass back of the head 7 and retain the plungers in position. 7 When the plunger is advanced the conical head 7 rides under the shoulder 17 lifting the locking plate until the head 7 passes beyond the plate when the plate drops down back of the head, thus preventing its return until the plate is again lifted. If 7 to a greater extent so that the previously operated plunger is released.

In order that the locking plate 16 may be lifted to release any plunger which has been pushed in when the use of the telephone is discontinued, devices are provided for lifting the locking plate when the receiver is hung up and then immediately allowing the loclring plate to return to normal position ready to look any plunger which may be subsequently pushed in. This device consists of a latch or dog 18 which is carried by the telephone arm or bar. In the construction shown the latch 18 is pivoted to the inner end of the arm 19 upon which the telephone receiver is suspended. This telephone arm is of the usual construction and is forced yieldingly upward by a spring 20 so that it swings upward into the position indicated in Fig. 5 when the telephone receiver is removed and is returned into the position indicated in Fig. 1, when the telephone receiver is replaced. The latch 18' is provided with a lip 21 so arranged that it will underlie a lug 22 formed on the upper end of the locking plate when the telephone arm 19 is in the position indicated in Fig. 5. The latch 18 is so proportioned and pivoted that its weight tends to swing it toward the left and its swinging movement in this direction is limited and controlled by a fixed lug 23 arranged to cooperate with an inclined or cam surface 24 on the latch. When the telephone arm 19 is held in the position indicated in Fig. 1 by the weight of the receiver, the latch 18 is held in the position indicated in Fig. 1 by the lug 23 and in this position the lip 21 is to the right of the lug 22 on the locking plate. With the parts in this position the locking plate is free to rise and fall under the action of the heads 7 of the plungers 2. JV hen the receiver is removed from the arm 19 the arm swings up into the position indicated in Fig. 5. This movement of the arm carries the latch 18 downward, the vertical surface 25 on the latch riding against the side of the lug 22 on the locking plate until the lip 21 passes below the lug when the latch 18 swings toward the left bringing the lip 21 under the lug 22 as indicated in Fig. 5. Now when the receiver is replaced upon the arm 19 and the arm swings into the position indicated in Fig. 1, the latch acts to lift the locking plate and as the latch moves upward the inclined or cam surface 24 rides against the lug 23 forcing the latch toward the right as indicated in Fig. 6. After the locking plate has been lifted sufficiently to release any of the plungers which have been pushed in the movement of the latch toward the right by the action of the lug 23 and inclined surface 24 disengages the lip 21 from the lug 22 allowing the locking plate to return to normal position. This latch forms a verv simple and efhcient device for lifting and releasing the locking plate when the receiver is replaced upon its supporting arm or bar and forms one of the features of the invention.

The locking plate is mounted between the arms 26 of two U-shaped plates 27 which eX- tend horizontally from the contact plate 5, the locking bar being guided in slots formed in the inner sides of said arms. These horizontal plates 27 also form supports for suporting a contact plate 28 which is arranged In front of the plungers 2 in such position that the inward movement of the )lungers will bring them into contact with the plate. The contact plate 28 is however so arranged with relation to the locking plate that the heads of the plungers will be out of engagement with the contact plate when the heads are engaged by the locking plate. This contact plate 28 is connected through a wire 280 with the ringing battery circuit so that the engagement of a plunger with this contact plate causes the bell to ring at the station corresponding to tne plunger operated. The contact plate 28 is insulated from the supporting plates 27 by strips of insulating material 29 introduced between the contact plate and the upper edges of the plates 27. The plate of insulating material 29 is secured. upon the contact plate 28 and projects beyond the sides of said plate where it is engaged by the contact springs 12 and thus prevents accidental engagement of said springs with the plate 28. A protecting plate 30 may be arranged over the ends of the contact springs 12 and may be secured in position by nuts 31 threaded on to the studs 32 which extend from the supporting plate 27.

The switch mechanism may be provided with the usual contact plates 38 arranged to be operated and controlled in the usual manner by the movement of the telephone arm 19.

The construction described forms a very simple, inexpensive and compact switch mechanism which is reliable and ellicient in operation and which is not liable to get out of order.

Without attempting to point out in detail the various constructions in which the features of invention may be embodied, what I claim is 1. A switch mechanism for inter-communicating telephone systems comprising a contact plate, a series of plungers sliding through said plate, a contact plate in front of all the plungers, a contact spring at the side of each plunger, and a locking plate for retaining each plunger in engagement with the corresponding contact spring, substantially as described.

2. A switch mechanism for inter-communicating telephone systems comprising a contact plate, a series of plungers sliding through said plate, a contact plate in front of all the plungers, a contact spring at the side of each plunger, a lockin plate arranged between the two contact p ates, a series of shoulders on the locking plate, and a cot) aerating conical head on each plunger, the ength of the head being less than the distance between the locking plate and the contact plate in front of the plungers, substantially as described. r

3. A switch mechanism for inter-communicating telephone systems comprising a contact plate 5, a series of plungers 2 sliding through said plate, contact springs 12 provided with contact portions projecting mto the path of the plungers, a contact plate 28 in front of the plungers, an insulating plate 29 projecting beyond the edges of the late 28 and preventing the engagement 0 the contact springs therewith, and a locking plate for retaining the plungers 1n enga ement with the contact springs, substantially .15

HENRY O. THOMSON.

'Witnesses:

CHARLES W. WILKINS, ROBERT J. LONERGAN. 

